From patchwork Mon Jul 22 21:39:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11053505 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4B0BE1398 for ; Mon, 22 Jul 2019 21:41:34 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3CD442847E for ; Mon, 22 Jul 2019 21:41:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 31170284DB; Mon, 22 Jul 2019 21:41:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id CA9682847E for ; Mon, 22 Jul 2019 21:41:33 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg2b-0002XY-9v; Mon, 22 Jul 2019 21:40:17 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg2a-0002VI-3k for xen-devel@lists.xenproject.org; Mon, 22 Jul 2019 21:40:16 +0000 X-Inumbo-ID: 4a6588d4-acc9-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 4a6588d4-acc9-11e9-8980-bc764e045a96; Mon, 22 Jul 2019 21:40:14 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B071F344; Mon, 22 Jul 2019 14:40:14 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09D303F71F; Mon, 22 Jul 2019 14:40:13 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 22 Jul 2019 22:39:33 +0100 Message-Id: <20190722213958.5761-11-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190722213958.5761-1-julien.grall@arm.com> References: <20190722213958.5761-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v2 10/35] xen/arm64: head: Improve coding style and document create_pages_tables() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Adjust the coding style used in the comments within create_pages_tables() Lastly, document the behavior and the main registers usage within the function. Note that x25 is now only used within the function, so it does not need to be part of the common register. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- xen/arch/arm/arm64/head.S | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index ddc5167020..eddf663021 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -70,7 +70,7 @@ * x22 - is_secondary_cpu * x23 - UART address * x24 - - * x25 - identity map in place + * x25 - * x26 - skip_zero_bss (boot cpu only) * x27 - * x28 - @@ -436,16 +436,27 @@ cpu_init: ret ENDPROC(cpu_init) +/* + * Rebuild the boot pagetable's first-level entries. The structure + * is described in mm.c. + * + * After the CPU enables paging it will add the fixmap mapping + * to these page tables, however this may clash with the 1:1 + * mapping. So each CPU must rebuild the page tables here with + * the 1:1 in place. + * + * Inputs: + * x19: paddr(start) + * x20: phys offset + * + * Clobbers x0 - x4, x25 + * + * Register usage within this function: + * x25: Identity map in place + */ create_page_tables: - /* Rebuild the boot pagetable's first-level entries. The structure - * is described in mm.c. - * - * After the CPU enables paging it will add the fixmap mapping - * to these page tables, however this may clash with the 1:1 - * mapping. So each CPU must rebuild the page tables here with - * the 1:1 in place. */ - - /* If Xen is loaded at exactly XEN_VIRT_START then we don't + /* + * If Xen is loaded at exactly XEN_VIRT_START then we don't * need an additional 1:1 mapping, the virtual mapping will * suffice. */ @@ -469,7 +480,8 @@ create_page_tables: cbz x1, 1f /* It's in slot 0, map in boot_first * or boot_second later on */ - /* Level zero does not support superpage mappings, so we have + /* + * Level zero does not support superpage mappings, so we have * to use an extra first level page in which we create a 1GB mapping. */ load_paddr x2, boot_first_id